Apparatus for feeding granular material into a fluid stream



13, 1947. w, THQMAS 2,420,388

APPARATUS FOR FEEDING GRANULAR MATERIAL INTO A FLUID STREAM Filed Dec. 29, 1945 Q Iv Ki INVENTOR N m MOW/9074 7%?0/7 6:

Patented May 13, 1947 APPARATUS FOR FEEDING GRANULAR MATERIAL INTO A FLUID STREAM William A. Thomas, Pittsburgh, Pa., assignor to Blaw-Knox Company, Pittsburgh, Pa., a corporation of New Jersey Application December 29, 1945, Serial No. 637,819

11 Claims.

This invention relates to apparatus for feeding granular material and, in particular, to a feeder adapted to introduce material into a confined space against a predetermined back pressure ex- 2 about the common axis of the gas nozzle and Venturi tube. The invention also contemplates suitable driving means for rotating the scraper blade.

isting therein, A complete understanding of the invention may In many industrial operations, particles of solid be obtained from the following detailed descripmaterial are conveyed through a pipe by entraintion thereof which refers to the accompanying ment in a gas stream flowing therethrough. It is drawing illustrating a present preferred embodifrequently desirable to introduce solid particles ment. In the drawings, into such a conveying stream against the static Fi ure 1 is a sectional view taken along the pressure of the gas in the pipe. Gas-jet injectors central vertical plane, with parts in elevation; have been used for this purpose. Usually, the and motive fluid for the injector is the same as that Figure 2 is a transverse section taken along the circulating through the pipe although this is not plane of line II--II of Figure 1. necessarily so. If the solid material entering the Referring now in detail to the drawings, the conveying stream is delivered withoutbeing conapparatus of my invention comprises an injec or trolled, an excess of material will usually be It! including a base plate H, a feed box l2 and a drawn into the conveying stream and an objecbarrel l3. The feed box is composed of upper tionable loud whistling noise is produced. and lower plates l4 and 15, a rear plate l5a and While gas-jet injectors serve satisfactorily for side plates [6. One of the side plate p e e y introducing solid materials into a gas stream has a tight fitting clean-out door l6 hinged against the pressure thereof, under favorable con thereto adjacent the base plate I I. The material ditions, certain materials have a tendency to build to be fed is delivered to the upper end of the box up accumulations in the form of a crust at the I2 by any suitable means such as a laterally exentrance into the Venturi tube usually incorpotending screw conveyor ll. The upper end of the rated in the injector. These accumulations obbox I2 is closed by a plate l8 thereon having an struct the Venturi tube and tend to close on the air inlet fitted with a silencer in the form of a passage therethrough, eventually rendering the conventional air filter l9. injector inoperative. This is aggravated if the A flange plate 20 is welded to the forward edges material being fed has a substantial moisture of the upper plate [4 and the side plates [6 of the content. feed box'and the base plate II. A barrel 2i in I have invented anovel form of means for feedthe form of a cylinder or pipe 22 having terminal ing granular material into a confined space flanges 23 and 24 welded thereon extends foragainst back pressure. My invention embodies a, wardly from the plate 20. A Venturi tube 25 is gas-jet injector and means for periodically scrapremovably disposed in the barrel, the forward end ing the entrance end of the Venturi tube thereof thereof seating against the flange 24 and the rear to prevent the accumulation of solid material end thereof having a shoulder 26 accommodated thereon and to scoop up any particles which may in a, recess formed by counterbores in the adjacent be temporarily deposited thereon and return them faces of the plate 20 and flange 23. The flange 23 to the gas stream through the injector. In a preis secured to the plate 20 by screws 21 with sealing ferred embodiment, my invention comprises an gaskets between their mating surfaces and also injector including the usual Venturi tube and between them and the opposite faces of the shoulnozzle for delivering a jet of motive fluid thereder 26 of the Venturi tube 25. The plate 20 has through. A feed box delivers material to be fed a conical central opening 20a, forming a continat the entrance end of the Venturi tube and a uation of the entrance to the throat of the tube scraper means mounted for rotation about a fixed '25. The flange plate 20 may serve for mounting axis extends into the entrance end of the Venturi the entire feeding mechanism on a suitable suptube for wiping or sweeping movement thereport and the flange 24 may be secured to the pipe, around. Conveniently, the scraper means has the duct or other passage or container to which the form of a fiat blade and is mounted for rotation material is to be fed.

2,42o,aas ,7

' 'rne feed as i2 and the barrel 2i. define a' gas-tight passage for the flow of granular materlal under the impact of a gas jet, A nozzle 28 for discharging such jet is disposed coaxially of the Venturi tube 25, being mounted at the end of a gas-supply pipe 29 extending rearwardly therefrom. The pipe 29 extends through a ear box 30 defined by the base plate I I, the rear plate lia of the feed box, a side plate 3|, 9, top plate 32 and an end plate 33. The pipe is connected to any suitable source of motive fluid under pressure, e. g., superheated steam. The rear end of the pipe is threaded to accommodate nuts 34. By turning these nuts, the pipe 29 may be adjusted toward and from the entrance to the Venturi tube.

A sleeve bearing 35 is positioned in the gear box 30 coaxial with the pipe 29, being mounted on the rear wall lid of the feed box by screws 36. A hollow shaft 31 is journaled in the bearing 35 and projects forwardly into the feed box ii. The pipe 29 extends through this shaft. Scraping means in the form of a flat plate or blade 38 is mounted on the shaft 31 by means of clamping yokes 39. The forward end of the plate extends into the entrance and of the Venturi tube 25 and is shaped to conform thereto as indicated at 38a. It will be apparent that, on rotation of the shaft 31, the blade rotates bodily about the common axis of the pipe 29, nozzle 28 and Venturi tube 25, and serves to wipe or scrape off any granular material which may have accumulated in the entrance end of the tube.

A laterally extending shaft 40 is joumaled in a bearing carried by the side wall 3| of the gear box and is driven by any suitable means such as a pulley 4| and belt 42. A bevel pinion 43 on the shaft 40 meshes with a bevel gear 44 secured to the-rear end of the hollow shaft 31. The shaft 40 may be driven by a separate motor or from the shaft of the conveyor H. In any event, the drive should be such that the shaft 31 is rotated at a speed of about eight to ten revolutions per minute.

It will be apparent from the foregoing that the invention provides injector means for feeding granular material to a confined space against a back pressure existing therein, having provision for preventing the building up of accumulations of material at the entrance of the Venturi tube of the feeding injector which might obstruct the latter or eventually completely clog it. The slow rotation of the scraper blade not only removes any accumulations which might tend to stick to the entrance to the Venturi tube but also stirs up material in the body of the feed box adjacent thereto and subjects itto the inspirating effect of the gas jet. The invention is particularly adapted for delivering coal to an impact grinder wherein the coal particles as fed are so actuated by steamjet injectors as to cause fragmentation thereof by collision. A particular advantage of the invention in this type of installation is that it makes possible the handling of coal having a moisture content as high as Attempts to feed this type of coal into a pulverizer by an ordinary injector have resulted in the building up of substantial deposits of material at the entrance to the Venturi tube which obstruct the proper functioning thereof if they do no close it altogether. A similar condition is encountered in feeding other materials such as sulphur, clay, limestone or the like if a substantial amount of moisture is present therein. The invention thus makes it possible to burn certain grades of coal in a pulverized fuel burner which could not be pulverized by other means, such as a ball mill because of the tendency to form a paste which clogs up the mill and defies mechanical handling.

Although I have illustrated and described but a preferred embodiment of the invention, it will be recognized that changes in the details of construction disclosed may be made without departing from the spirit of the invention or the scope of the appended claims.

I claim:

1. In an apparatus for feeding granular material into a fluid stream, the combination with a fluid-jet injector including a nozzle and a Venturi tube, of a scraper blade extending generally axially into the entrance of said tube, and means mounting. said blade for rotation about a fixed axis.

2. In an apparatus for feeding granular material into a fluid stream, the combination with a fluid-jet injector including a nozzle and a Venturi tube, of a scraper blade extending generally axially into the entrance of said tube, and means mounting said blade for rotation about the axis of said nozzle.

3. In an apparatus for feeding granular material into a fluid stream, the combination with a fluid-jet injector including a nozzle and a Venturi tube, of a scraper blade extending generally axially into the entrance of said tube, and means rotatable about said nozzle for supporting said blade.

4. Inan apparatus for feeding granular material into a fluid stream, the combination with a fluid-jet injector including a nozzle and a Venturi tube, and a feed box adapted to deliver material to the entrance of said tube, of a sleeve rotatable on said nozzle, and a scraper blade mounted on said sleeve and extending into said entrance.

5. In an apparatus for feeding granular material into a fluid stream, the combination with a fluid-jet injector including a nozzle and a Venturi tube, of rotary scraper means for preventing accumulation of said material at the entrance to said tube, and means for driving said scraper means.

6. In an apparatus for feeding granular material into a'fluid stream, the combination with a fluid-jet injector including a nozzle and a Venturi tube, of a scraper blade extending generally axially into the entrance of said tube, a sleeve rotatable on said nozzle, said blade being mounted on said sleeve, and means for driving said sleeve.

7. In an apparatus for feeding granular material into a fluid stream including a Venturi tube, a nozzle discharging into the tube coaxlally thereof, and means for feeding granular material into the entrance of said tube, the improvement comprising scraper means extending into said tube, means mounting said scraper means for rotation, and means for driving said mounting means.

8. In an apparatus for feeding granular material into a fluid stream including a Venturi tube, a nozzle discharging into the tube coaxially thereof, and means for feeding granular material into the entrance of said tube, the improvement comprising a sleeve rotatable about said nozzle, a scraper blade mounted on said sleeve and extending into the entrance of said tube, and means for driving said sleeve.

v9. In an apparatus for feeding granular material into a fluid stream including a Venturi tube, a nozzle discharging into the tube coaxially thereof, and means for feeding granular matea feed box adapted to deliver material to said 15 1,970,405

tube, and means mounted for rotation about said nozzle adapted to scrape accumulations of material from the entrance to said tube.

WILLIAM A. THOMAS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 1 Number Name Date 50,153 Palmer Sept. 26, 1865 423,121 Brown Mar. 11, 1890 822,379 Luckenback June 5, 1906 1,835,603 Kincaid Dec. 8, 1931 Thomas Aug. 14, 193i 

